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TY - CONF AU - Nakanishi, K. AU - Hirosawa, K. AU - Kobayashi, T. AU - Nishiwaki, M. ED - Li, Ying-ying ED - Li, Lu ED - Schaa, Volker RW TI - SRF System for KEKB and SuperKEKB J2 - Proc. of eeFACT2018, Hong Kong, China, 24-27 September 2018 CY - Hong Kong, China T2 - ICFA ABDW on High Luminosity Circular e$^+$e$^-$ Colliders T3 - 62 LA - english AB - Eight superconducting accelerating cavities were operated for more than ten years at the KEKB. Commisioning operation of SuperKEKB is ongoing and those cavities are also used to accelerate the electron beam of 2.6 A. There are some issues to address the large beam current and to realize stable operation. One issue is a large HOM power of 37 kW expected to be induced in each cavity module. To cope with the HOM power issue, we have installed an additional HOM damper to the downstream of the cavity module. Another issue is degradation of Q values of the cavities during the ten years operation. Cause of the degradation was particle contamination. To clean the cavity surface, high pressure rinsing (HPR) is an effective way. Therefore we have developed a horizontal HPR. In this method, a nozzle for water jet is inserted horizontally into the cavity module without disassembly of the cavity. We applied the horizontal HPR to our degraded cavities. The RF performances of those cavities have been successfully recovered. In this report, present status of our cavity will be presented. Additionally, LLRF control issues for SuperKEKB will be introduced. PB - JACoW Publishing CP - Geneva, Switzerland SP - 256 EP - 263 KW - cavity KW - operation KW - controls KW - HOM KW - LLRF DA - 2019/04 PY - 2019 SN - 978-3-95450-216-5 DO - DOI: 10.18429/JACoW-eeFACT2018-WEYAA03 UR - http://jacow.org/eefact2018/papers/weyaa03.pdf ER -